Tuning the emissivity of 3D macroporous silicon in the mid-infrared

Abstract

Tailoring the thermal emission of a particular material by using periodic micro-structures has attracted great interest for its potential applications in heating and lighting systems or thermophotovoltaics. […] Metallic and dielectric gratings, can be designed to introduce sharp emissions peaks which can be controlled with the grating parameters. 3D photonic band gap materials are particularly flexible in managing and confining light and, therefore, they are excellent candidates for controlling thermal radiation. Macroporous silicon, consisting of periodic arrays of etched pores in hydrofluoric acid solution, is a versatile material that provides large-area, high-quality and thermally-stable microstructures. It features full three-dimensionality, well controlled pore distribution and growth, and scalable dimensions in a range from 0.5 μm up to 100 μm. Silicon 3D structures operate at infrared wavelengths, efficiently reducing the emissivity inside the PBG regions. We present several Si microstructures and their emissivity/reflectivity responses measured by FT-IR spectrometry.